This invention relates to a distributed propulsion system for a multi-unit articulated road train, and more specifically, the invention relates to a system for controlling and coordinating multiple propulsion systems.
Many commercial vehicles for use on highways employ a tractor that pulls a trailer that holds cargo. Typically, the tractor has a propulsion system that includes an internal combustion engine, usually diesel, and a transmission and drive axle. The trailer and its cargo are simply pulled by the drive force generated by the tractor""s propulsion system. Accordingly, the tractor must be able to generate enough drive force to propel both the tractor and the trailer. Often several trailers are pulled by the tractor to increase the cargo that the tractor is able to deliver to a destination. As a result, the tractor must be capable of pulling the combined load of each trailer and its associated cargo. However, the same tractor at other times may only pull one trailer, or none at all, which results in enormous inefficiencies because the tractor""s propulsion system may be grossly overpowered for the given task.
Trailers having separate propulsion systems have been used so that a tractor or other lead vehicle is not required to generate a drive force to pull the trailer. It is necessary to coordinate the propulsion systems of the tractor and trailer so that the vehicle may operate safely. This is especially important for multi-unit road trains having two or more trailers because of the increasing vehicle instability and possibility of jack-knifing as trailers are added to the train. Load sensors have been incorporated between the units to actuate the propulsion system of the trailer when a tensile load is detected. However, this type of propulsion system is unable to coordinate multiple units with one another and each unit acts independently from the other. Furthermore, the response of each trailer lags since a tensile load is required between each unit before the unit will begin to propel itself. As a result, for a road train, the last unit will not begin to move, until every single unit in front of it has begun to move, one at a time. Therefore, what is needed is a distributed propulsion system that is capable of coordinating each unit and achieving a faster response time for improved control.
The present invention provides a distributed propulsion system for a multi-unit articulated road train. The distributed propulsion system includes a tractor having a first propulsion system for propelling the tractor. A trailer is secured to the tractor at an articulated joint, such as a fifth wheel or draw bar connection. The tractor has a second propulsion system for substantially propelling the trailer. A load sensor for detecting a load between the tractor and the trailer, preferably the tensile load, is associated with the articulated joint. The load sensor produces a load signal. An input device produces a request signal for actuating the second propulsion system. An electronic control mechanism is electrically connected to the input device and the load sensor for coordinating the various sensors and inputs. The control mechanism commands the second propulsion system in response to the load signal and the request signal such that the trailer is propelled in a controlled manner relative to the tractor.
Accordingly, the above invention provides a distributed propulsion system that is capable of coordinating each unit and achieving a faster response time for improved control.